This invention relates generally to an isocyanate-terminated prepolymer produced from biological materials.
The use of triglycerides in preparation of alkyd resins is well known. Typically, these resins are produced without modifying the fatty acid chains, but rather by utilizing the triglyceride ester groups to react with acids and glycols to form polyesters. Such resins usually have high molecular weights and require solvent to deliver the resin in a coating application.
Production of condensation products useful in paints from reaction of triglycerides with maleic anhydride, followed by reaction with ethylene glycol has been described. For example, U.S. Pat. No. 2,188,882 to Clocker discloses the reaction of linseed oil with 10% by weight maleic anhydride at 250° C., followed by reaction of the product with a small amount of ethylene glycol at about 180° C. However, the material produced in this way is extremely viscous and must be dispersed in a solvent to be used. A prepolymer made from a hydroxy-functional material derived from biological materials which has a relatively low viscosity and is useable in a solvent-free composition would be a desirable product.